Fix printf() format problems with configurable prompts

U-Boot allows for configurable prompt strings using the
CONFIG_AUTOBOOT_PROMPT resp. CONFIG_MENUPROMPT definitions. So far,
the assumption was that any such user defined problts would contain
exactly one "%d" format specifier. But some boards did not.

To allow for flexible boot prompts without adding too complex code we
now allow to specify the whole list of printf() arguments in the user
definition. This is powerful, but requires a responsible user who
really understands what he is doing, as he needs to know for exanple
which variables are available in the respective context.

Signed-off-by: Wolfgang Denk <wd@denx.de>

1 files changed, 11 insertions, 4 deletions

diff --git a/doc/README.autoboot b/doc/README.autoboot
index e4c4186..2042fe5 100644
--- a/doc/README.autoboot
+++ b/doc/README.autoboot
@@ -114,10 +114,17 @@ What they do
 	CONFIG_AUTOBOOT_PROMPT is displayed before the boot delay
 	selected by CONFIG_BOOTDELAY starts. If it is not defined
 	there is no output indicating that autoboot is in progress.
-	If "%d" is included, it is replaced by the number of seconds
-	remaining before autoboot will start, but it does not count
-	down the seconds. "autoboot in %d seconds\n" is a reasonable
-	prompt.
+
+	Note that CONFIG_AUTOBOOT_PROMPT is used as the (only)
+	argument to a printf() call, so it may contain '%' format
+	specifications, provided that it also includes, sepearated by
+	commas exactly like in a printf statement, the required
+	arguments. It is the responsibility of the user to select only
+	such arguments that are valid in the given context. A
+	reasonable prompt could be defined as
+
+		#define CONFIG_AUTOBOOT_PROMPT \
+			"autoboot in %d seconds\n",bootdelay
 
 	If CONFIG_AUTOBOOT_DELAY_STR or "bootdelaykey" is specified
 	and this string is received from console input before